Sintering ceramic for stable high-temperature thermistors and method for producing the same

Abstract

A sintering ceramic for stable high-temperature thermistors includes a system of matter containing manganese (IV) and a content of a basic oxide. A method for producing a sintering ceramic for stable high-temperature thermistors includes calcining a mixture of SrCO3 and Mn2O3 or Mn3O4; adding an oxide hydroxide of a dopant in a molar quantity x to an aqueous suspension of the calcined oxide mixture; and then carrying out a compacting densification of the system of matter.

We claim: 
     
       1. A sintering ceramic for stable high-temperature thermistors, comprising a composition of the formula Sr 7  M x  Mn 4-x  O 15 , in which M is a dopant selected from the group consisting of scandium, yttrium, lanthanum, rare earth elements, zirconium, niobium and tantalum, and x is a doping amount greater than zero. 
     
     
       2. The sintering ceramic according to claim 1, wherein said dopant is selected from the group consisting of scandium, zirconium, niobium and tantalum. 
     
     
       3. A method for producing a sintering ceramic for stable high-temperature thermistors, which comprises: calcining a mixture of SrCO 3  and a substance selected from the group consisting of Mn 2  O 3  and Mn 3  O 4  ;   adding an oxide hydroxide of a dopant in a molar quantity x to an aqueous suspension of the calcined oxide mixture to form a composition of the formula Sr 7  M x  Mn 4-x  O 15  in which M is a dopant selected from the group consisting of scandium, yttrium, lanthanum, rare earth elements, zirconium, niobium and tantalum, and x is a doping amount greater than zero; and   then carrying out a compacting densification of the composition.   
     
     
       4. The sintering ceramic according to claim 1, wherein said dopant is selected from the group consisting of yttrium and lanthanum. 
     
     
       5. The sintering ceramic according to claim 1, wherein said dopant is an element of the rare earths. 
     
     
       6. The method according to claim 3, which comprises producing thermistor tablets from the composition by compacting shaping, and sintering the tablets at a temperature in the range of 1550° C.